Plume-top altitude time-series during May 2011 volcanic eruption of Grímsvötn, Iceland

Plume-top altitude time series of the volcanic plume during the eruption of Grímsvötn in Iceland 21-28 May 2011. The altitude was estimated from weather radar echo top data from two weather radars, Keflavik and Klaustur. Keflavik radar is a fixed position C-band weather radar close to Keflavik International Airport, at 64°01.583'N, 22°38.150'W. The height of the antenna is 47 m a.s.l. and the distance to Grímsvötn volcano is 257 km. Klaustur radar is a mobile X-band weather radar located close to Kirkjubaejarklaustur, at 63°46.500'N, 17°57.817'W. The height of the antenna is also 47 m a.s.l. and the distance to Grímsvötn volcano is 75 km.

(Table 1) Characteristics of South Pole personnel according to forced expiratory flow (FEF25-75) response to altitude

The impact of acute altitude exposure on pulmonary function is variable. A large inter-individual variability in the changes in forced expiratory flows (FEFs) is reported with acute exposure to altitude, which is suggested to represent an interaction between several factors influencing bronchial tone such as changes in gas density, catecholamine stimulation, and mild interstitial edema. This study examined the association between FEF variability, acute mountain sickness (AMS) and various blood markers affecting bronchial tone (endothelin-1, vascular endothelial growth factor (VEGF), catecholamines, angiotensin II) in 102 individuals rapidly transported to the South Pole (2835 m). The mean FEF between 25 and 75% (FEF25-75) and blood markers were recorded at sea level and after the second night at altitude. AMS was assessed using Lake Louise questionnaires. FEF25-75 increased by an average of 12% with changes ranging from -26 to +59% from sea level to altitude. On the second day, AMS incidence was 36% and was higher in individuals with increases in FEF25-75 (41 vs. 22%, P = 0.05). Ascent to altitude induced an increase in endothelin-1 levels, with greater levels observed in individuals with decreased FEF25-75. Epinephrine levels increased with ascent to altitude and the response was six times larger in individuals with decreased FEF25-75. Greater levels of endothelin-1 in individuals with decreased FEF25-75 suggest a response consistent with pulmonary hypertension and/or mild interstitial edema, while epinephrine may be upregulated in these individuals to clear lung fluid through stimulation of beta2-adrenergic receptors.

Abb. 3 Change of altitude in the EGIG-West-East-profile

The members of the two International Glaciological Greenland Expeditions (EGIG) in 1959 and 1968 determined the altitudes in the West-East-profile by levelling. The comparison of these two measurements gives evidence of the change of altitudes and of the surface-waves. The ways of measurement and of analysis are described here. The graphic representation of the result is discussed here in connexion with the possible causes.

Plume-top altitude time-series during 2010 volcanic eruption of Eyjafjallajökull

The eruption of Eyjafjallajökull volcano in 2010 lasted for 39 days, 14 April-23 May. The eruption had two explosive phases separated by a phase with lava formation and reduced explosive activity. The height of the plume was monitored every 5 min with a C-band weather radar located in Keflavík International Airport, 155 km distance from the volcano. Furthermore, several web cameras were mounted with a view of the volcano, and their images saved every five seconds. Time series of the plume-top altitude were constructed from the radar observations and images from a web camera located in the village Hvolsvöllur at 34 km distance from the volcano. This paper presents the independent radar and web camera time series and performs cross validation.